Hinged safety switches are known to be used in plants or machines having areas or rooms bounded by protection barriers, and containing mechanical moving members or hazardous devices.
Particularly, these safety switches are mounted to a protection barrier having a fixed part integral with the machine or plant, and a movable panel designed to be opened by an operator.
Hinged safety switches have casing designed to be secured to the fixed part of the barrier and a movable part, which can pivot relative to the enclosure, and is designed to be secured to the panel.
Furthermore, the switch comprises an electrical commutator and an actuator, which is adapted to interact with such commutator upon pivotal movement of the movable part.
As the panel is opened and/or closed, the movable part of the switch is caused to pivot relative to the casing and the actuator is triggered.
This latter will thus actuate the commutator to cause one or more electric safety circuits associated with the barrier to open and/or close.
A very common type of hinged safety switches uses mechanical commutators.
IT1362135, filed by the applicant hereof, discloses a safety switch with a mechanical commutator housed within the casing. This commutator comprises one or more movable contacts, moving along a longitudinal axis, whose displacement is driven by an actuator which is adapted to convert the rotary motion of the movable part into an axial translational motion.
Furthermore, this prior art switch may comprise LED-type optical signaling means, for confirming proper operation of the contacts and indicating where actuation occurs.
A first drawback of this prior art arrangement is that the use of mechanical commutators does not easily allow generation of electric signals with additional information concerning the position of the barrier or the state of the switch.
This is because mechanical commutators only allow switching of electrical contacts associated with safety circuits and cannot determine any inconsistent switching states of the contacts or wiring or contact unit failures.
A further drawback of this arrangement is that switches with mechanical commutators cannot be easily installed in safety plants that use a data bus or a field bus connected to an electronic control unit.
The installation of hinged safety devices with analog contact units requires an appropriate analog-to-digital conversion interface, such as AS-i or the like, to be interposed between the bus and the contacts, which will increase installation costs and circuit complexity of the electrical system.